The present invention relates generally to a device for determining the required size and shapes of dentures or partials and more particularly to a device for determining tentative centric occlusion and registration of the upper and a lower bite of a dental patient.
The type of food we eat, how fast and for how long depends on the neuromusculature. Therefore, neuromusculature is the governor of mandibular function. During the dentulous state of an individual the masticatory apparatus functions in centric occlusion (C.O.). When the teeth are gone, we do not know how to find the centric occlusion, except that we know that the muscles function most efficiently when in centric occlusion. Therefore, until now, centric relation has been used when dentition is lost in the effort to find the centric occlusion. It has also been suggested by well known authors that the point of centric occlusion is located one or two millimeters in front of the point of centric relation. Somewhere anterior to centric relation is the point of function as determined by the neuromusculature. When we find that position, we set our teeth to it. It is at that position that the patient is functioning at functional occlusion and masticates his food most efficiently.
When one attempts to lift a chair, it is much easier to lift the chair closer to the body because the muscles of the trunk and arms function better when the load is nearer the fulcrum and the muscles always brace themselves toward the center of the body or fulcrum. The mandible is likewise efficient. Toward the posterior, in the area of the second molar, the mandible functions maximally. When the mandible is braced to the glenoid fossa by the vectors and directions of the muscle fibers, the mandible in this state is in functional occlusion. However, if we attempt to push or position the mandible with finger pressure, we introduce a non-functional stimulus and, therefore, we might be in centric relation or other positions but not the functional occlusal position because the soft tissue around the bony condyle is artificially compressed.
It will be appreciated by those skilled in the art that in order to fit dentures, one must record a tentative horizontal maxilla-mandibular relationship in the partially and fully edentulous mouth. Further, the face-bow registration of the patient must also be recorded, as well as the vertical dimension of occlusion. Unfortunately, in the past, obtaining these measurements has been time consuming, typically taking one of the four or more separate visits to the dentist in order to deliver a completed, properly fitting denture. One of the primary reasons for this in the prior art is the inability of prior art devices to register adequate soft tissue (gingival) likeness while preventing distortions by the use of a harder wax bite. It is known that materials in contact with tissue be bi-laterally uniform in firmness, inert, and non-abrasive, all at ambient physiological temperatures.
One prior art method and device is disclosed in U.S. Pat. No. 4,657,509 issued to P. Morris on Apr. 14, 1987. The Morris patent discloses an impression tray which is malleable at temperatures of 150.degree. Fahrenheit yet rigid at body temperature. Unfortunately, this device has one consistent layer of material and does not distinguish the need between obtaining impression of the existing teeth versus the impression of the exposed gingiva.
Another such device is disclosed in U.S. Pat. No. 3,217,067 issued to R. Tencate on Nov. 9, 1965. Like Morris, Tencate fails to recognize the difference in texture between existing teeth and exposed gingiva.
U.S. Pat. No. 3,663,141 issued to A. Clenet, et al. on Feb. 26, 1970 discloses an impression device in which two halves of an impression are made separately. One-half of the impression is made of the exposed buccal tissue whereas the other half is made of the existing teeth. Unfortunately, this device requires four different molds, two for the upper and two for the lower.
U.S. Pat. No. 4,115,488 issued to R. Colpitts on Sep. 19, 1978, discloses a single layer impression. Unfortunately, like much of the prior art, Colpitts fails to recognize the difference in texture of the exposed gingiva from the existing teeth.
U.S. Pat. No. 4,307,044 issued R. Perez on Dec. 22, 1981, also discloses a single layer impression which fails to recognize the difference in texture of the exposed gingiva from the existing teeth.
U.S. Pat. No. 4,517,043 issued to R. Martin, et al on May 14, 1985, discloses a single layered impression which fails to recognize the difference in texture of the exposed gingiva from the existing teeth.
U.S. Pat. No. 4,846,682 issued to Ootsubo on Jul. 11, 1989, discloses a single layered impression which fails to recognize the difference in texture of the exposed gingiva from the existing teeth.
U.S. Pat. No. 4,983,331 issued to T. Wise on Jan. 8, 1991, discloses the use of a single layered impression which fails to recognize the difference in texture of the exposed gingiva from the existing teeth.
U.S. Pat. No. 5,059,120 issued to R. Lee on Oct. 22, 1991, discloses a handle having impression pads which are of the same consistency throughout.
U.S. Pat. No. 4,745,961 issued to A. Salandra on May 24, 1988, discloses a single layered impression. Although the Salandra patent discloses the use of beeswax, it is merely used as a coating for a set-up and is not used for multi-layered impressions.
U.S. Pat. No. 3,813,777 issued to A. Van Handel, et al on Jun. 4, 1974 discloses a single layered impression. Although the Van Handel patent discloses a layer of wax over a layer of plastic, the plastic is not impressed.
What is needed, then, is a device which recognizes the difference in exposed gingiva tissue as compared to existing teeth. This needed device must record the tentative horizontal maxilla-mandibular relationship or centric occlusion in the partially or fully edentulous mouth. This needed device must help record the arbitrary face-bow registration. This device must establish and record the tentative vertical dimension of occlusion. This device must eliminate at least one of the chair-side appointments of health compromised patients. This device must be used in connection with a three, as opposed to a four, appointment denture technique. This device is presently lacking in the prior art.